Motor fuel



Uit rates 3,036,905 Patented May 29, 1962 3,036,905 MOTOR FUEL Martin Hamcr, Chicago, Ill., assignor to Standard (Bil Company, Chicago, Ill., a corporation of Indiana No Drawing. Filed Sept. 3, 1957, Ser. No. 681,434 13 Claims. (CI. 44-66) The invention relates to improvements in the suppression of surface ignition and reduction of octane require ment increase of leaded fuels in the operation of sparkignition internal combustion engines. More particularly, this invention provides leaded fuels containing novel additives which are effective in suppressing surface ignition and reducing octane requirement increase.

it is known that the presence of organolead antiknock agents, such as tetraethyllead, in the fuel burned in a spark-ignition internal combustion engine leads to the formation of combustion chamber deposits which are detrimental to the efficient operation of the engine. In spite of the use of lead scavenging agents, these deposits continue to grow in amount as the engine is operated until an equilibrium condition is reached in which the rate of formation of deposits equals the rate of removal in the exhaust gases and no further accumulation occurs. These deposits are harmful in that they cause an increase in the octane rating of the fuel needed for knock-free operation compared to that needed with the engine in a clean condition, which increase is known as the octane requirement increase (R1) of the engine operating on the particular fuel. Another difliculty which is created by the presence of combustion chamber deposits from leaded fuels is surface ignition, i.e., the ignition of the fuel charge either before or after the passage of the spark caused by glowing of carbon deposits. Deposits from leaded fuels are largely responsible for this condition, since lead salts are known to lower the glow point of carbon.

It is an object of this invention to provide leaded fuel compositions for spark-ignition internal combustion engines which have a minimum tendency to promote surface ignition and increase octane requirement. A further object is to provide new and improved additives for addition to motor fuels for spark-ignition internal combustion engines in order to achieve these beneficial results.

I have discovered that the above objects can be achieved by providing a fuel comprising a major proportion of a hydrocarbon mixture boiling within the gasoline distillation range, minor amounts of an organolead antiknock compound and a halohydrocarbon lead scavenger, and an oil soluble mercury compound in an amount sufficient to reduce the susceptibility of the fuel to surface ignition, and preferably in an amount sufiicient to give a mole ratio of mercury to lead in the fuel within the range from about 0.01 to about 1.0. In an advantageous embodiment the mercury compound, the halohydrocarbon scavenger, and the organolead antiknock compound are made up as a concentrate in a solvent oil vehicle. The concentrate may then be conveniently added in the required quantities to the hydrocarbon fuel before use, thus providing a finished fuel composition of the required octane rating which is inhibited against surface ignition and has a minimum tendency to increase the octane requirement of the engine.

In accordance with my invention there must be present in the combustion chamber of an engine operated on a leaded fuel a small but effective proportion of a mercury compound. Although any practicable method of introducing the mercury compound into the combustion chamber can be used, as by injecting it in solution as a sepa- 2. rate stream, it is most convenient and thus the preferred embodiment of the invention, to dissolve the mercury compound in the fuel. The nature of the mercury compound does not appear to be controlling provided that it is sufiiciently oil soluble for use in the fuel, since it is believed that under the conditions which obtain in the combustion chamber of the engine during use the same end product, probably mercuric oxide, results regardless of the original identity of the mercury compound. In the course of my investigations, I have found that oilsoluble mercury salts of monocarboxylic acids are eminently suitable for use in my invention. Of these, mercury naphthenate and mercury oleate are particularly advantageous examples. Other useful mercury compounds, by way of example, are soaps of mercury and fatty acids, such as mercury stearate, chelates of mercury and B- diketones, such as mercury acetylacetonate, and mercury alkyl phenolates, such as mercury octyl phenolate. Whatever the mercury compounds used, it is preferred, although not essential, to use a suflicient amount in order to yield in the finished fuel composition a mole ratio of mercury to lead within the about 1.0.

The lead antiknock compound which is used in this invention can be any of the organolead compounds which are useful for this purpose. By organolead compound is meant any compound in which the lead is directly linked to carbon atoms. Examples of suitable compounds are the lead aryls such as tet-naphenyllead and the lead alkyls, particularly the tetra-alkyls, such as tetramethyllead, tetraethyllead, tetrapropyllead, tetrabutyllead, dimethyldiethyllcad and the like, as well as mixtures of such compounds. Because of its availability and superior operating characteristics tetraethyllead is the preferred organolead antiknock agent. It is customarily used at a concentration of about 0.5 cc. to 5.00 cc. per gallon of fuel.

The fuel compositions of my invention contain, as is customary with leaded fuels, the usual lead scavenging compounds,the use of which is essential for satisfactory operation of the engine. These scavengers aid in the removal of much of the lead which would otherwise be deposited within the combustion chamber by combining with the lead to form volatile compounds which are removed in the engine exhaust gases. Scavengers are customarily halogenated hydrocarbons having about 2 to 8 carbon atoms and 2 to 3 or more halogen, especially bromine iand/or chlorine, atoms per molecule. They are used in fuels in amounts of about 0.5 to 1.5 theories, a theory being defined as the amount stoichiometrically re quired for reaction with the lead present in the fuel to produce the lead dihalide. Examples of suitable scavengers are ethylene dichloride, ethylene dibromide, trichloropropane, chlorodibromobutane, trichlorocyclopentane, bromoethylbenzene and the like, as well as mixtures of these compounds. Ethylene dichloride and ethylene dibromide, which are in commercial use, are the preferred scavengers for use in my invention.

The motor fuel used in this invention is preferably gasoline, but may be any other combustible liquid of suitable volatility commonly used as fuel for spark-ignition internal combustion engines, including par-aflinic, naphthenic and aromatic hydrocarbons. The boiling point of such fuels should be in the range from about F. to about 500 F., and preferably in the range from F. to about 400 F. The fuel may also contain other ingredients commonly found in finished fuel compositions, such range from about 0.01 to as anti-oxidants, stabilizers, dyes, anti-icing agents and the like.

Although in most cases it will be found most convenient to add the mercury compounds of my invention to a finished fuel composition already containing the lead antiknock agent, it is also contemplated that an additive mixture be provided for addition to the fuel, which miX- ture contains the antiknock agent, tetraethyl lead for example, the halohydrocarbon scavenger, and the mercury compound in an amount to give a mole ratio of mercury to lead within the range of about 0.01 to about 1.0. The additive combination may be made up in any suitable solvent oil facilitating blending into the finished fuel, for example, naphtha, light gas oil, catalytic cycle oil, light lubricating oil fractions, or aromatic solvents such as benzene, toluene, Xylenes and the like. Sufficient solvent oil should be used to provide desirable fluidity, for example, within the range of 25% to about 95% or more based on the total weight of the additive mixture. The additive combination may also contain desirable amounts of other common ingredients such as dyes, stabilizers, and the like.

Without being limited to any theory of the method by which the additives of my invention provide beneficial results, I believe these additives help in two ways to improve the operation of the engines to which they are used. The mercury compound may assist the halohydrocarbon scavenging agent in the removal of the combustion chamber deposits, thereby minimizing ORI and surface ignition caused by the deposits. In addition, the mercury compound may provide a catalytically active material which counteracts the tendency of the lead deposits which remain within the combustion chamber to promote the glowing of carbon particles. Thus, even in those instances when little or no reduction in combustion chamber deposits results from the use of the additives of my invention, there is nevertheless a decrease in ORI and surface ignition due to deposits.

As specific embodiments of my invention, the following examples are given. It is to be understood that these are by way of illustration only and are not intended as a limitation of my invention.

EXAMPLE I Combustion Chamber Deposit Weight (g) Base Fuel+ Percent Base .0375% Mer- Mole Reduc- Fucl 1 cury Naph- Ratio, tion in thenate Hg/Pb Deposit Weight Lauson Engine No. 1 5. 80 3.95 0.1 32 Lauson Engine No. 2 6.14 3. 66 0.1 40

1 Gasoline containing 3 cc. TEL/gaL, 1.0 theory of ethylene dichloride, and 0.5 theory of ethylene dibromide.

As can be seen from the above data the presence of he mercury naphthenate resulted in a reduction in deposit weight of 30 to 40%.

EXAMPLE II The benefits obtained in using the additives of my invention were further demonstrated by the results obtained in a CFR overhead valve engine in 165-hour cycled runs under the following conditions:

1 Gasoline containin 3 cc. TEL/gal.,1.0 theory of ethylene dichloride, and 0.5 theory of ethylene dibrornide.

Z Mole ratio H2/Pb=0.1.

These data illustrate the marked decrease in deposit harm, as evidenced by the large reduction in octane requirement increase and surface ignltion, which results from the use of the additives of my invention.

EXAMPLE III Further tests with a 17.6 D.C. single cylinder engine again demonstrated the reduction in ORI which follows from the use of the mercury compounds of this invention. The tests used in each case were 165 hour cycled runs carried out under the following conditions:

Cycle Compression Ratio, 7.7-Load. None Full Coolant Temp, F., 148i3-T1me, sec 45 Oil Temp., 11, 160:1:5-Speed, r.p.n1 r. 900 000 Intake Air, Temp, F., 110;l=5Air/Fuel Ratio 12. 5 13. 5

Results were as follows:

Base Fuel+ Percent Base 0.0375% Hg Improve- Fuel 1 Naphthcmerit nate 2 Octane Requirement Increase 14. 5 5.0 G6

EXAMPLE IV The effectiveness of the mercury compounds of my invention is further demonstrated by the results obtained on 150 hour cycled runs with a 1953 Pontiac 8-cylinder engine. The runs were carried out under the following conditions.

. Once an hour a Duration" 45 sec. 13:) sec.

- 2 000 r.p,m. 1(10 Cycle Errgieei 100 r.p.m...- 2,000 r.p.m o'pen throttle Load None 26mg celeratlon for .30

SOC.

Corn resslon ratlo-7.0:1. Air/ uel rati0-AS found. Coolant temp.=t:5 F. Oil temp.105;t=5 F.

The addition of mercury naphthenate to the fuel caused a significant decrease in the amount of combustion cham- Base Fuel+ Percent Base 0.0375% Hg Improve- Fuel 1 Naphthe ment mate 3 Deposit Wt, (g) 2 85. 6 68. 5 20 Octane Requirement Increase 2 3.8 3.0 21

TABLE 1 Induction Octane Period Rating (min) 1 (Research) Gasoline A (3.0 cc. TEL/gaL, 1.5 theories halohydrocarbon scavengers) 455 92. 2 Gasoline A+0,0375% Hg naphthenate (mole ratio Hg/Pb=0.l) 120 92. 2

! ASTM D525-49.

While I have described my invention by reference to specific embodiments thereof, the same are given by way of illustration only. Modifications and variations will be apparent from my description to those skilled in the art.

I claim:

1. A fuel composition for a spark ignition internal combustion engine comprising a major proportion of a hydrocarbon mixture boiling within the gasoline distillation range, from about 0.5 to about 5.0 cc. per gallon of fuel of an organolead antiknock compound, from about 0.5 to about 1.5 theories of a halohydrocarbon scavenger, and an oil soluble mercury compound capable of forming mercury oxide under spark ignition internal combustion engine combustion chamber conditions, said mercury compound being present in an amount suflicient to reduce the susceptibility of said fuel composition to surface ignition.

2. The fuel composition of claim 1 in which said mercury compound is mercury naphthenate.

3. The fuel composition of claim 1 in which said mercury compound is mercury oleate.

4. The fuel composition of claim 1 in which said antiknock compound is tetraethyllead.

5. A fuel composition for a spark ignition internal combustion engine comprising a major proportion of gasoline, tetraethyllead in an amount from about 0.5 to about 5.0 cc. per gallon of gasoline, from about 0.5 to about 1.5 theories of a halohydrocarbon lead scavenger, and an oil soluble mercury compound capable of forming mercury oxide under spark ignition internal combustion engine combustion chamber conditions, said mercury compound being present in an amount suflicient to give a mole ratio of mercury to lead in the range from about 0.01 to about 1.0.

6. A fuel composition for a spark ignition internal combustion engine comprising a major proportion of gasoiine, tetraethyllead in an amount from about 0.5 to about 5.0 cc. per gallon of gasoline, from about 0.5 to about 1.5 theories of a halohydrocarbon lead scavenger, and an oil soluble mercury salt of a monocarboxylic acid in an amount sufficient to give a mole ratio of mercury to lead in the range from about 0.01 to about 1.0.

7. The fuel composition of claim 6 in which said mercury salt is mercury naphthenate.

8. The fuel composition of claim 6 in which said mercury salt is mercury oleate.

9. An additive combination for gasoline consisting essentially of an organolead antiknock compound, from about 0.5 to about 1.5 theories of a halohydrocarbon lead scavenger, and an oil soluble mercury compound capable of forming mercury oxide under spark ignition internal combustion engine combustion chamber conditions, said mercury compound being present in an amount sufiicient to give a mole ratio of mercury to lead in the range from about 0.01 to about 1.0.

10. The additive composition of claim 9 in which said organolead antiknock compound is tetraethyllead.

11. The additive composition of claim 9 in which said mercury compound is mercury naphthenate.

12. The additive composition of claim 9 in which said mercury compound is mercury oleate.

13. In a spark ignition internal combustion engine using a hydrocarbon fuel containing an organo-lead antiknock composition and a halohydrocarbon scavenger the method of reducing octane requirement increase and surface ignition in the combustion chamber of the spark ignition internal combustion engine which comprises introducing oxygen and an oil-soluble mercury compound capable of forming mercury oxide under spark ignition internal combustion engine combustion chamber conditions in the presence of said hydrocarbon fuel containing from about 0.5 to about 5.0 cc. per gallon of fuel of an organo-lead antiknock composition and from about 0.5

to about 1.5 theories of a halohydrocarbon scavenger into the combustion chamber.

References Cited in the file of this patent UNITED STATES PATENTS 1,841,254 Rosenbaum Jan. 12, 1932 2,151,432 Lyons et al Mar. 21, 1939 2,258,297 Miller et a1. n Oct. 7, 1941 2,314,575 Doran Mar. 23, 1943 2,356,476 Shappirio Aug. 22, 1944 2,364,921 Shokal Dec. 12, 1944 2,671,758 Rubin et a1 Mar. 9, 1954 2,926,184 Irish et a1 Feb. 23, 1960 2,933,330 Kegelman Apr. 19, 1960 

1. A FUEL COMPOSITION FOR A SPARK IGNITION INTERNAL COMBUSTION ENGINE COMPRISING A MAJOR PROPORTION OF A HYDROCARBON MIXTURE BOILING WITHILN THE GASOLINE DISTILLATION RANGE, FROM ABOUT 0.5 TO ABOUT 5.0 CC. PER GALLON OF FUEL OF AN ORGANOLEAD ANTIKNOCK COMPOUND, FROM ABOUT 0.5 TO ABOUT 1.5 THEORIES OF A HALOHYDROCARBON SCAVENGER, AND AN OIL SOLUBEL MERCURY COMPOUND CAPABLE OF FORMING MERCURY OXIDE UNDER SPARK IGNITION INTERNAL COMBUSTION ENGINE COMBUSTION CHAMBER CONDITIONS, SAID MERCURY COMPOUNDS BEING PRESENT IN AN ALMOUNT SUFFICIENT TO REDUCE THE SUSCEPTIBILITY OF SAID FUEL COMPOSITION TO SURFACE IGNITION.
 3. THE FUEL COMPOSITION OF CLAIM 1 IN WHICH SAID MERCURY COMPOUND IS MERCURY OLEATE. 